A sad sight: The lifeless body of the porpoise (pictured) was found floating in Cardigan Bay, West Wales, by a research team on Wednesday

A sustained attack: Dr Salomé Dussan-Duque, monitoring officer for Sea Watch Foundation, claimed the attack left the porpoise (pictured being tossed in the air) unable to swim after the dolphins repeatedly hit its side

THE HARBOUR PORPOISE

The harbour porpoise (Phocoena phocoena) is one of six species of porpoise.

It is one of the smallest marine mammals and typically stays close to the coast or in river estuaries.

The creature gets its name from Medieval Latin poropiscus, which means pig fish.

Harbour porpoises have been known to dive 721 feet (220 metres) and can hold their breath for up to five minutes.

Up until 2008, scientists were baffled about why quite large numbers of the small marine mammals were found dead - and the U.S. navy was even blamed for scores of dead porpoises in Virginia.

But then tell-tale teeth marks were identified and examinations of the harbour porpoises' bodies revealed broken ribs, imploding lungs and internal bleeding, from prolonged dolphin attacks, The Telegraph reported.

Most cases of the attacks have been documented along the east coast of Scotland and off the coast of Virginia.

She said: ‘We saw the much larger dolphins hitting the animal on its side.’

‘This violent behaviour is not unusual between these two species.

‘However, the opportunity to witness it so close at hand and to be able to record it so well is quite special.’

Harbour porpoises measure almost four feet (1.2metres) and five feet (1.5metres) long when fully grown, and are dwarfed by their larger cousins, the bottlenose dolphin.

Bottlenose dolphins in UK waters can reach up to 14 feet (4.3 metres) in length, which is the largest size for this species of dolphin anywhere in the world.

The assault was observed by a research team from Sea Watch Foundation who were aboard a boat called the Dunbar Castle, run by New Quay Dolphin Spotting Boat Trips.

Another team, who discovered the dead porpoise days later, reported their find to the UK Cetacean Strandings Investigation Programme (CSIP).

The group deals with all reports of dead and stranded whales, dolphins and porpoises, and conducts post-mortems where appropriate.

The CSIP team will now investigate the cause of death of the porpoise but the condition of the animal looked consistent with bottlenose dolphin attacks previously observed.

Examinations of some harbour porpoises after an attack have previously revealed broken ribs, imploding lungs and massive internal bleeding.

The assault (pictured) was observed by a research team from Sea Watch Foundation who were aboard a boat called Dunbar Castle. Here, the porpoise is flipped upside down by a dolphin attacking from below